Data from: Enemy at the gates: rapid defensive trait diversification in an adaptive radiation of lizards

Adaptive radiation, the product of rapid diversification of an ancestral species into novel adaptive zones, has become pivotal in our understanding of biodiversity. While it has widely been accepted that predators may drive the process of adaptive radiation by creating ecological opportunity (e.g. enemy-free space), the role of predators as selective agents in defensive trait diversification remains controversial. Using phylogenetic comparative methods, we provide evidence for an ‘early burst’ in the diversification of antipredator phenotypes in Cordylinae, a relatively small adaptive radiation of morphologically diverse southern African lizards. The evolution of body armour appears to have been initially rapid, but slowed down over time, consistent with the ecological niche-filling model. We suggest that the observed ‘early burst’ pattern could be attributed to shifts in vulnerability to different types of predators (i.e. aerial versus terrestrial) associated with thermal habitat partitioning. These results provide empirical evidence supporting the hypothesis that predators or the interaction therewith might be key components of ecological opportunity, though the way in which predators influence morphological diversification requires further study.

适应辐射（Adaptive radiation）指祖先物种快速分化并侵入全新适应区的演化产物，现已成为我们理解生物多样性的核心研究议题。尽管学界已普遍认可捕食者可通过创造生态机会（如无天敌空间（enemy-free space））驱动适应辐射进程，但捕食者作为选择压力介导防御性状分化的作用仍存在广泛争议。本研究采用系统发育比较分析法（phylogenetic comparative methods），对绳蜥亚科（Cordylinae）——一类形态多样、规模相对较小的南非本土蜥蜴适应辐射类群——的反捕食表型（antipredator phenotypes）分化展开研究，为该类群的表型分化存在"早期爆发"模式提供了实证依据。体甲的演化初始阶段速度较快，但随时间推移逐渐放缓，这与生态位填充模型的理论预测一致。我们推测，本次观测到的"早期爆发"模式可归因于与热生境分区相关的不同捕食者类型（即空中捕食者与陆生捕食者）所带来的被捕食易感性变化。上述结果为"捕食者及其种间相互作用或为生态机会的关键组成部分"这一假说提供了经验证据，不过捕食者影响形态性状分化的具体路径仍有待进一步深入研究。